Sunday, August 07, 2011

To decarbonate everything

To answer the title question, eating a banana is a very carbon-friendly way to snack. The book is How Bad are Bananas? The Carbon Footprint of Everything by Mike Berners-Lee. Make that almost everything. If you want to compare the carbon footprint of washing plastic or ceramic dishes versus using disposable paper plates, you won't find it here, but you will find nearly any other carbon-using or -saving option that there is.

I suppose there is a way to finesse the wash-versus-discard question, because there is a section on paper bags, with a carbon footprint of 12-80g CO2e (meaning "carbon dioxide equivalent") each, depending on size and decoration and transport. There he states, "The paper industry is highly energy intensive." He goes on to discuss the energetics of paper manufacture on a per-kilo or per-pound basis, whether it is virgin or recycled, and also the carbon release by landfilling used paper rather than recycling it. You can then calculate how many kilos of paper plates you might use, that are equivalent to a dishwasher load, and compare the result with 770-990g per load, a bit more than doing them carefully by hand.

Just now much CO2e does a banana represent? About 80g each, or 480g/kg. That includes shipping them half across the world. Compare apples at 550g/kg and oranges at 500 g/kg. Of course, if you grow any of these yourself, and don't need to water your trees, the net CO2e is zero. They absorb carbon dioxide as they grow and release it upon use (via your sewage and trash). All the CO2e of plant foods is in watering, fertilizer, transport and marketing.

At the other end of the scale, are you considering having a new house built? For a 2-3 bedroom bungalow, the CO2e is 50 Tons! For a house like mine (4Br, 2Ba, full Bsmt), double that or more. The book is arranged by intensity, starting at 1-10g CO2e, up to millions and even billions, for whole national economies and finally, for the World, meaning all of human civilization. One item never mentioned: human activities amount to about 2% of the trillions of Tons of CO2e represented by the geologic and hydrologic cycles. However, this seemingly small amount is enough to unbalance the system a little, which is why there is global warming.

A word on CO2e itself. Carbon dioxide is one of four prominent greenhouse gases. The most important is water vapor. Without the greenhouse energy trapping provided by water, Earth's average temperature would be sixty degrees F cooler than it is. Think Alaskan weather in Bermuda, and sea ice everywhere north of Los Angeles and Miami (and Morocco and Hyderabad; and similarly in the southern hemisphere). The other two are nitrous oxide, which is around 300 times as potent at CO2, and methane, at about 25 times the potency. These two break down in the atmosphere over a few years' time, however, so the calculation of CO2e depends on the time frame. They have a large effect on 10-20 year time spans, and comparatively little over fifty years. There is a small, and fortunately shrinking, level of refrigerant gases. Though more refrigeration and air conditioning are being produced each year, the chemical companies are producing better refrigerants with a smaller carbon footprint per pound or per kilo.

Throughout the book the author compares various actions with a "10-Ton lifestyle". Considering that the average Western family's present footprint is in the 15-20 Ton range, that represents quite a bit of frugality going forward. For example, over the past few years we have replaced all the windows in our 60-year-old house with tighter, more energy-efficient ones, and going back ten years or more we have replaced nearly all light bulbs with CFL's. I'd opt for LED's, but at current prices of around $30 each, they are less worth it than when CFL's were $15 some twelve years ago. My price point for LED's is $12. I can get equivalent CFL's for $6. I take my burnouts to a mercury recycler. I have spent close to $20,000, hoping for a long-term payback, but a lower-energy lifestyle in the meantime. But I am nowhere near a 10-Ton level.

Not surprisingly, transport is one of the heavy hitters. Unless a human walks or cycles everywhere, moving that heavy body (50kg and up) takes lots of energy, and most of that is liquid fuel, gasoline or diesel. Traveling about 800 miles in a small, efficient automobile produces 330 kg CO2e. For my car, it is more like 500, which is why we rent a modern economy car for road trips. That figure of 500 is the same as a one-person plane ride of the same distance. If my wife and I both go, my car is twice as efficient as the airplane, per person, and even more so in the rental car. A recent drive from the Philadelphia area to near Kansas City, Missouri in a car with 36 highway mpg was a revelation. Fill-ups were needed rarely, and the tank only held 11 gallons. My 12-year-old Camry gets 26 mpg on the road, so its 18-gallon tank will actually go a little farther, but needs 50% more gas to fill. One of the best decisions of my life was getting a house that is only three miles from my workplace. My commute puts less than 1,500 miles on my car each year.

The book was a great deal of fun to read. I like facts, and this is a veritable encyclopedia of CO2e information, with suggestions of reducing your own carbon impact in practical ways, ways that address the big factors while not sweating the small stuff. Mike Berners-Lee is a special advisor to Crichton Carbon Centre and founding director of Small World Consulting.